[IR] Add Type::getFloatingPointTy.

[ebevhan]

Summary

It is possible to get a fltSemantics of a particular Type,
but there is no way to produce a Type based on a
fltSemantics.

This adds the function Type::getFloatingPointTy, which
will return the appropriate floating point Type for a given
fltSemantics.

ConstantFP is modified to use this function instead of
implementing it itself. Also some minor refactors to use
Type::getFltSemantics instead of a hand-rolled version.

[rjmccall]

LGTM, thanks!

llvm/include/llvm/IR/Type.h

if (std::is_integral<ScalarTy>::value) {
       case 32:
         return Type::getFloatTy(C);
       case 64:
         return Type::getDoubleTy(C);
       }
     }
     llvm_unreachable("Unsupported type in Type::getScalarTy");
   }
+  static Type *getFloatingPointTy(LLVMContext &C, const fltSemantics &S) {
+    Type *Ty;
+    if (&S == &APFloat::IEEEhalf())
+      Ty = Type::getHalfTy(C);
+    else if (&S == &APFloat::BFloat())
+      Ty = Type::getBFloatTy(C);
+    else if (&S == &APFloat::IEEEsingle())
+      Ty = Type::getFloatTy(C);
+    else if (&S == &APFloat::IEEEdouble())
+      Ty = Type::getDoubleTy(C);
+    else if (&S == &APFloat::x87DoubleExtended())
+      Ty = Type::getX86_FP80Ty(C);
+    else if (&S == &APFloat::IEEEquad())
+      Ty = Type::getFP128Ty(C);
+    else {
+      assert(&S == &APFloat::PPCDoubleDouble() && "Unknown FP format");
+      Ty = Type::getPPC_FP128Ty(C);
+    }
+    return Ty;
+  }
 
   //===--------------------------------------------------------------------===//
   // Convenience methods for getting pointer types with one of the above builtin
   // types as pointee.
   //
   static PointerType *getHalfPtrTy(LLVMContext &C, unsigned AS = 0);
   static PointerType *getBFloatPtrTy(LLVMContext &C, unsigned AS = 0);
   static PointerType *getFloatPtrTy(LLVMContext &C, unsigned AS = 0);

llvm/lib/IR/Constants.cpp

 void ConstantInt::destroyConstantImpl() {
   llvm_unreachable("You can't ConstantInt->destroyConstantImpl()!");
 }
 
 //===----------------------------------------------------------------------===//
 //                                ConstantFP
 //===----------------------------------------------------------------------===//
 
-static const fltSemantics *TypeToFloatSemantics(Type *Ty) {
-  if (Ty->isHalfTy())
-    return &APFloat::IEEEhalf();
-  if (Ty->isBFloatTy())
-    return &APFloat::BFloat();
-  if (Ty->isFloatTy())
-    return &APFloat::IEEEsingle();
-  if (Ty->isDoubleTy())
-    return &APFloat::IEEEdouble();
-  if (Ty->isX86_FP80Ty())
-    return &APFloat::x87DoubleExtended();
-  else if (Ty->isFP128Ty())
-    return &APFloat::IEEEquad();
-
-  assert(Ty->isPPC_FP128Ty() && "Unknown FP format");
-  return &APFloat::PPCDoubleDouble();
-}
-
 Constant *ConstantFP::get(Type *Ty, double V) {
   LLVMContext &Context = Ty->getContext();
 
   APFloat FV(V);
   bool ignored;
-  FV.convert(*TypeToFloatSemantics(Ty->getScalarType()),
+  FV.convert(Ty->getScalarType()->getFltSemantics(),
              APFloat::rmNearestTiesToEven, &ignored);
   Constant *C = get(Context, FV);
 
   // For vectors, broadcast the value.
   if (VectorType *VTy = dyn_cast<VectorType>(Ty))
     return ConstantVector::getSplat(VTy->getElementCount(), C);
 
   return C;
if (auto *VTy = dyn_cast<VectorType>(Ty))
     return ConstantVector::getSplat(VTy->getElementCount(), C);
 
   return C;
 }
 
 Constant *ConstantFP::get(Type *Ty, StringRef Str) {
   LLVMContext &Context = Ty->getContext();
 
-  APFloat FV(*TypeToFloatSemantics(Ty->getScalarType()), Str);
+  APFloat FV(Ty->getScalarType()->getFltSemantics(), Str);
   Constant *C = get(Context, FV);
 
   // For vectors, broadcast the value.
   if (VectorType *VTy = dyn_cast<VectorType>(Ty))
     return ConstantVector::getSplat(VTy->getElementCount(), C);
 
   return C;
 }
 
 Constant *ConstantFP::getNaN(Type *Ty, bool Negative, uint64_t Payload) {
-  const fltSemantics &Semantics = *TypeToFloatSemantics(Ty->getScalarType());
+  const fltSemantics &Semantics = Ty->getScalarType()->getFltSemantics();
   APFloat NaN = APFloat::getNaN(Semantics, Negative, Payload);
   Constant *C = get(Ty->getContext(), NaN);
 
   if (VectorType *VTy = dyn_cast<VectorType>(Ty))
     return ConstantVector::getSplat(VTy->getElementCount(), C);
 
   return C;
 }
 
 Constant *ConstantFP::getQNaN(Type *Ty, bool Negative, APInt *Payload) {
-  const fltSemantics &Semantics = *TypeToFloatSemantics(Ty->getScalarType());
+  const fltSemantics &Semantics = Ty->getScalarType()->getFltSemantics();
   APFloat NaN = APFloat::getQNaN(Semantics, Negative, Payload);
   Constant *C = get(Ty->getContext(), NaN);
 
   if (VectorType *VTy = dyn_cast<VectorType>(Ty))
     return ConstantVector::getSplat(VTy->getElementCount(), C);
 
   return C;
 }
 
 Constant *ConstantFP::getSNaN(Type *Ty, bool Negative, APInt *Payload) {
-  const fltSemantics &Semantics = *TypeToFloatSemantics(Ty->getScalarType());
+  const fltSemantics &Semantics = Ty->getScalarType()->getFltSemantics();
   APFloat NaN = APFloat::getSNaN(Semantics, Negative, Payload);
   Constant *C = get(Ty->getContext(), NaN);
 
   if (VectorType *VTy = dyn_cast<VectorType>(Ty))
     return ConstantVector::getSplat(VTy->getElementCount(), C);
 
   return C;
 }
 
 Constant *ConstantFP::getNegativeZero(Type *Ty) {
-  const fltSemantics &Semantics = *TypeToFloatSemantics(Ty->getScalarType());
+  const fltSemantics &Semantics = Ty->getScalarType()->getFltSemantics();
   APFloat NegZero = APFloat::getZero(Semantics, /*Negative=*/true);
   Constant *C = get(Ty->getContext(), NegZero);
 
   if (VectorType *VTy = dyn_cast<VectorType>(Ty))
     return ConstantVector::getSplat(VTy->getElementCount(), C);
 
   return C;
 }

 
 // ConstantFP accessors.
 ConstantFP* ConstantFP::get(LLVMContext &Context, const APFloat& V) {
   LLVMContextImpl* pImpl = Context.pImpl;
 
   std::unique_ptr<ConstantFP> &Slot = pImpl->FPConstants[V];
 
   if (!Slot) {
-    Type *Ty;
-    if (&V.getSemantics() == &APFloat::IEEEhalf())
-      Ty = Type::getHalfTy(Context);
-    else if (&V.getSemantics() == &APFloat::BFloat())
-      Ty = Type::getBFloatTy(Context);
-    else if (&V.getSemantics() == &APFloat::IEEEsingle())
-      Ty = Type::getFloatTy(Context);
-    else if (&V.getSemantics() == &APFloat::IEEEdouble())
-      Ty = Type::getDoubleTy(Context);
-    else if (&V.getSemantics() == &APFloat::x87DoubleExtended())
-      Ty = Type::getX86_FP80Ty(Context);
-    else if (&V.getSemantics() == &APFloat::IEEEquad())
-      Ty = Type::getFP128Ty(Context);
-    else {
-      assert(&V.getSemantics() == &APFloat::PPCDoubleDouble() &&
-             "Unknown FP format");
-      Ty = Type::getPPC_FP128Ty(Context);
-    }
+    Type *Ty = Type::getFloatingPointTy(Context, V.getSemantics());
     Slot.reset(new ConstantFP(Ty, V));
   }
 
   return Slot.get();
 }
 
 Constant *ConstantFP::getInfinity(Type *Ty, bool Negative) {
-  const fltSemantics &Semantics = *TypeToFloatSemantics(Ty->getScalarType());
+  const fltSemantics &Semantics = Ty->getScalarType()->getFltSemantics();
   Constant *C = get(Ty->getContext(), APFloat::getInf(Semantics, Negative));
 
   if (VectorType *VTy = dyn_cast<VectorType>(Ty))
     return ConstantVector::getSplat(VTy->getElementCount(), C);
 
   return C;
 }
 
 ConstantFP::ConstantFP(Type *Ty, const APFloat &V)
     : ConstantData(Ty, ConstantFPVal), Val(V) {
-  assert(&V.getSemantics() == TypeToFloatSemantics(Ty) &&
+  assert(&V.getSemantics() == &Ty->getFltSemantics() &&
          "FP type Mismatch");
 }
 
 bool ConstantFP::isExactlyValue(const APFloat &V) const {
   return Val.bitwiseIsEqual(V);
 }
 
 /// Remove the constant from the constant table.